Lawyers for jailed terror chief Michael McKevitt alleged in the High Court that FBI spy David Rupert took no part when his former handlers |refused to pay him more. During closing submissions at the landmark legal case being brought against five men held responsible for the atrocity which claimed 29 lives, Rupert was portrayed as a fraudster who was ready and willing to perjure himself.

The trucking boss-turned intelligence agent was a key prosecution witness at the criminal trial in Dublin in 2003 when McKevitt was convicted of directing terrorism.

But Michael O’Higgins SC urged Mr Justice Morgan to take note of his failure to appear at the multi-million pound compensation case, or even to give evidence by video-link.

The barrister, representing McKevitt, stressed how lawyers for the victims’ families who brought the lawsuit had tried in vain to get an explanation from the FBI about why Rupert was not being supplied.

He said: “It gives rise to the inference that Rupert fell out with the FBI over money.

“When his contract ran out he was looking for more money, they wouldn’t pay it and because the price wasn’t right he more or less told them in colloquial terms ‘Hump off’.”

Mr O’Higgins compared the situation with the trial in Dublin where, he said, the FBI put in a “mammoth effort” to ensure Rupert’s attendance.

“The fact the shutters were literally pulled down and a responsible agency would not give any explanation is a huge cause for concern,” he claimed.

McKevitt, who is serving a 20-year-sentence for directing terrorism, Liam Campbell, Seamus McKenna, Colm Murphy and Seamus Daly are being sued by relatives of some of those killed in the August 1998 Real IRA attack on Omagh. All five men deny liability.

According to Mr O’Higgins, the |defence has suffered prejudice by not being able to cross-examine Rupert.

He told the court that he would have wanted to question the spy about meetings he claims to have had with McKevitt — encounters which were not witnessed by others.

“We say that nowhere in any of the conversations is there any suggestion Mr McKevitt was involved in the Omagh bombing,” the barrister said.

The court also heard that the grouping his client was alleged to have been “busy” in was not the Real IRA but a new organisation which drew on strands from three republican paramilitary factions.

Although Mr O’Higgins accepted the plaintiffs’ submissions that Rupert was not classed as an accomplice in the case, he argued that neither could he be described as an ordinary witness.

Referring to emails and correspondence from the businessman, the barrister said: “At all times, even when reading the document, bear in mind the mind which created it, and it’s a bad mind.”